A prior art notching machine of the kind as herein referred is described in German Patent No. 34 33 658. In this known notching machine an angular drive adjustment mechanism is being used for adjusting successively two angularly different turning positions of a pair of upper and lower set collars. The two set collars carry the upper and lower knives of a blade assembly which have a predetermined coinciding minimum vertex angle. Whenever a notching of workpieces with a notching angle greater than this minimum vertex angle is being desired it therefore becomes necessary to effect a notching of the workpieces in such two angularly different turning positions of the blade assembly with two correspondingly successive working strokes of the vertically moving ram of the notching machine carrying the upper set collar with the upper knife.
The lower set collar carrying the lower knife forms an auxiliary table plane-parallel with the machine table. It has a hollow pivot member which carries a coaxially mounted ring gear. The same forms the final gear of a gearing which is a part of the angular drive adjustment mechanism driven by a numerically controlled direct current motor. The gearing also comprises a pinion meshing with this rather very large sized ring gear. Both gears as well as a support bearing for the hollow pivot member are arranged in a common lubrication chamber of the machine table. The bearing is supported by a tubular member which forms an axial extension of the hollow pivot member and communicates with a lower ejection opening for the clippings.
With an angular drive adjustment mechanism incorporating such a large sized ring gear and used for commonly turning the two set collars and the blade assembly whenever a notching angle greater than the vertex angle is being desired it becomes necessary to first move and later brake again correspondingly large centrifugal masses after each working stroke of the ram. This causes some serious problems for precisely approaching the two successive turning positions of the two set collars. The numerically controlled direct-current motor is therefore realized with a correspondingly expensive voltage control.
This invention accordingly deals with the object of providing a notching machine which uses a less expensive angular drive adjustment mechanism. The notching machine shall also allow a less critical approach of the two angularly different turning positions of the two set collars whenever a notching angle greater than the minimum vertex angle of the blade assembly is being chosen for the notching of workpieces.